Drop support for node 16

[frederikprijck]

Changes

With node16 going EOL on September 11 (see https://nodejs.org/en/blog/announcements/nodejs16-eol), it makes sense to drop support for node16 in the new major version.

References

https://nodejs.org/en/blog/announcements/nodejs16-eol

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All existing and new tests complete without errors